Treatment of rubber



Patented May 2, 1933 aeeae ie PATENT @FFEQE WILLIAM P. TER HORST, OF IPACKANACK LAKE, NEW' JERSEY, ASSIGNOR TO THE NAUGATUCK CHEMICAL COMPANY, OF NAUGATUCK, CONNECTICUT, A COREOBIATICN OF CONNECTICUT TREATMENT O1 RUBBER N0 Drawing. Original application filed. December 4, 1929, Serial No. 411,666. Divided and this application filed July 28, 1931.

This invention relates to the treatment of rubber and similar materials, more particularly to a treatment of the same with certain derivatives of reaction products of ketones and salts of aromatic amino compounds, and of rearranged reaction products of ketones and amino compounds. It also relates to the products of such treatment.

An object of this invention is to provide materials having the property of retarding the deterioration of rubber. Another object is to provide materials having the property of improving the resistance of rubber to abrasion; another object is to provide mate rials which prevent or retard cracking of tread stocks containing carbon black. A still further object is to provide materials having vulcanization-accelerating properties. Other objects will be apparent from the hereinsetforth description.

Accordingly the invention comprises treating rubber or similar materials with an aldehyde derivative of the reaction product of a ketone and a salt of an aromatic amino compound, or of a rearranged reaction product of a'ketone and an aromatic amino compound. Such materials are stable, and will when used in rubber exhibit at least one of the above mentioned properties.

Examples of reaction products of ketones and salts of aromatic amino compounds acetone-anilinehydrochloride, mesityl oxide-aniline-hydrochloride, diacetone alcoholanilinehydrochloride, acetone diphenyl guanidine hydrochloride, acetone-p,p-diamino-diphenyl methane hydrochloride, acetone-di-o-tolyl guanidine hydrochloride, acetone-o-tolyl biguanide hydrochloride, acetone-di-phenylamine hydrochloride, acetonephenyl-beta-naphthylamine hydrochloride, acetone-aniline acetate, acetone-o-toluidine hydrochloride, acetone 0, 0 diamino diphenyl sulfide hydrochloride.

Examples of rearranged reaction products of ketonesacetone-aniline rearranged in the presence of aniline hydrochloride, acetone-diphenyl guanidine rearranged in the presence of aniline hydrochloride, acetonealpha-naphthyl amine rearranged in the presence of aniline hydrochloride.

beta naphtli l Serial No. 55354 Examples of aldehyde derivatives read tion product of formaldehyde and the reaction product of acetone and aniline hydrochloride, reaction procuct of formaldehyde and the reaction product of diacetone alcohol and aniline hydrochloride, reaction product of formaldehyde and the reaction product of acetone and o-tolyl bignanide hydrochlo ride, reaction product of formaldehyde and the guanidine hydrochloride.

Instead of the ketones mentioned above the following may he used: phorone, diethyl ltetone, benzo phenone, aceto-phenone, dichloracetone, aldol acetone, allyl-acetone, benzal acetone, diacetyl, acetyl-acetone, acetonyl-acetonc, salicyl aldehyde-acetone, turfural-acetone.

Instead of the aromatic amino compounds mentioned above there may be used: monochloro aniline, ortho-toluidine, meta toluidine, para-toluidine, Xylidines, alpha'naphthylamine, naphthylamine, amino diphenyl, dinaphthylamines, asymmetric diphenyl hydrazine, diamino diphenyl sulphide, diamino diphenyl polysulphides, diamino dinaphthyl sulfides, p-amino benzyl-aniline, dinaphthyl diamino ethane, ditolyl diamino ethane, p-amino-pnaphthylamino diphenyl methane, diphenyl dimethyl methane, p-pdinaphthyl amino diphenyl dimethyi methane, phenyl guanidine, phenyl-o-tolyl guanidine, di-o-tolyl biguanide, monophenyl biguanide, diphenyl biguanide, diphenyl acetami ir e, o-phenylene diamine, m-phenylenc diamine, p-phonylene diamine, dimethyl p-phenyien diamine, m-toluylene diamine, benaidine, naphthylene diamine; 2,2diamino diphenyl; 2, i-diamino diphenyl; diphenyl-p-phenylene diamine, ditolylp-phenylene diamine, dinaphthyl-p-phenylene diamine, diphenyl-benzidine, dinaphthylbenzidine, naphthyl-m-toluylene diamine, dinaphthyl-m-toluylene diamine; QA-diam ino-diphenylamine; tfF-diamino diphenylamine; or mixtures of any of the foregoingaromat-ic amine compounds with a phenol such as phenol, alpha-naphthol, beta-naphthol.

In the reactions of ketones with salts of reaction product of acetone and diphenyl p-p-diamino aromatic amino compounds, such aromatic amino compounds as contain at least one ortho or para carbon atom linked to hydrogen, have been found to be most suitable.

The reaction may be carried out with or without the aid of a dehydrating agent. The following chemicals or mixtures thereof may be used as dehydrating agents: Calcium chloride, iodine, sulphanilic acid, hydrochloric acid, sulphuric acid, phosphorus pentoxide, sodium hydroxide, magnesium perchlorate, acetic acid, barium oxioe, zinc chloride, etc. It is an advantage to use the amine-addition product with zinc chloride, for example (G H NH ZnCl as a dehydrating agent.

Example 1R-eaction product of ketones and salts of amino compounds-By heating one mole of aniline hydrochloride and approximately four moles of acetone in an autoclave at 17 0 C. during 7 2 hours a reaction occurs during which methane is produced as a by-product. After cooling the reaction mixture, the methane is allowed to escape and the reaction product is freed from unreacted acetone. By neutralization with caustic soda and separation of the product a material is obtained which is a powerful antioxidant. The material is semi-solid and turns solid on standing. The results of tests in a tire tread compound are as follows:

is not definitely known.

Aniline-acetate may be used in place of aniline-hydrochloride in the reaction. In this case tire tread compounds tested for resistance to abrasion gave the following values:

Relative cure wear Blank 154 .75 parts of reaction product 181 E mampie 2 Diphenylguanidine hydrochloride was found to react readily with acetone. A temperature of 120 C. and a reaction time of 20 hours are required to obtain a practically complete reaction. In this case, again, methane is produced. The acetone-diphenylguanidine-hydroehloride reaction. product is prepared as follows:

211 grams diphenylguanidine (1 mole) are added to 110 grams 36% aqueous hydrochloric acid. The solution of diphenylguanidine hydrochloride is filtered through glass wool and can be used as such, without removal of water. 400 grams of acetone are added and the mixture is heated in an autoclave at 120 C. during 20 hours. After cooling, the methane formed is blown off, excess acetone is recovered and the hydrochloric acid is neutralized with 10% sodium hydroxide solution, The resulting product is an oil which float on top of the water layer. After separation from the water it can be used without further purification.

1.5 parts of the reaction product of acetone and diphenylguanidine hydrochloride per 100 parts of rubber are incorporated in the usual manner in a tire tread compound. The resulting stocks are aged in the oxygen bomb for 168 hours. A similar stock is made from which the antioxidant is omitted. The mix is vulcanized and aged under the same conditions. The tensile strengths before and after ageing are shown below.

Cure Tensiles +'reac- Before ageing Blank Lion product After ageing Ewample 3-Reaction product of acetone anld phenyl beta naphthylamine hydrochlo- IlC e.

7 1 grams of phenyl beta-naphthylamine are added to 10 grams of concentrated aqueous hydrochloric acid. The hydrochloride thus obtained is dried at 120 C. and yields 81.5 grams of phenyl beta-naphthylamine hydrochloride. 300 grams of acetone are added and the mixture is heated in an autoclave at 170l90 C. for 30 hrs. After cooling, the methane formed is blown off, excess acetone is recovered and the hydrochloric acid is neutralized with 10% caustic soda. solution. After separation from the water and drying, the reaction product is a brown powder; yield, about 111 grams.

1.5 parts of the reaction product of acetone and phenyl beta-naphthylamine hydrochloride per 100 parts of rubber are incorporated in the usual manner in a tire tread compoimd. The resulting stock is aged in an oxygen bomb. A similar stock is made from which the reaction product isomitted'. Thismix Cure Tensiles Blank Before ageing After ageing 168 hrs. in oxygen bomb After ageing 3 week at 158 F.

45' at 45%;. 1935 2953 60 at 45# 1758 3117 75 at 45# 1397 2950 at 45# 1440 3027 +reac- Tensiles before ageing Blank tion product 60 at 45# 4390 4325 .1 4275 4555 90 at 45# 4375 4205 After ageing 168 hrs. in oxygen bomb 60 at 45%; 1255 2585 75 at 45#. 1170 2335 90 at 45# 1065 2065 Example -30 parts of p,p-diamino diphenyl methaneare transformed into the hydrochloride either by adding concentrated hydrochloric acid to the amine and evaporating to dryness, or by dissolving or suspendin g p,p-diamino diphenyl methane in a minimum amount of acetone and passing dry hydrochloric acid gas through the mixture. Acetone is then added to the hydrochloride the mass is heated in an autoclave during hours at approximately 140 (3., in the presence of a small amount of iodine as a catalyst. The reaction mixture is then allowed to cool and the gas pressure is released by opening the valve of the autoclave. Excess acetone is then recovered by distillation and approximately 10% caustic soda solution is added in order to make the mass alkaline.

. '1 iereaction product usually floats on top of the aqueous solution and is separated. Low- .l;oiling material is removed by d1st1llat1on under vacuum. The final product is a brown powder having execellent antioxidant properties. The material was tested in the usual way. The results of the test were as follows:

v I +reac- Tensiles before ageing Blank tion product Ewample 6'100 parts of diphenylamine hydrochloride and 300 parts of acetone are heated in an autoclave during hrs. at 170 190 C. The oil obtained is filtered and neutralized with dilute aqueous sodium carbonate solution. 150 parts of the reaction product are obtained. 1 parts of the reaction product are incorporated in the usual manner in a standard tire tread compound containing 100 parts of rubber, parts carbon black and a mixture of 1 part of hexamethylene tetramine and .25 parts of diphenyl guanidine. A similar mix was made but omitting he reaction product. The mixes are vulcanized in a mold for minutes and 7 5 minutes at 45. pounds steam pressure. Samples of the resulting stocks are aged for 168 hours in the oxygen bomb, and for 3 weeks in air at 158 F. Values are given below:

Example 7()rtho toluidine hydrochloride and acetone are reacted in the same manner as in Example 6 to produce the re action product. 1 part of the reaction prodnot was used in the usual way in a standard tire tread compound containing 100 parts rubber. 42 partscarbon black .875 parts of dinitro phenyl dimethyl dithiocarbamate. A similar mix was made but omitting the reaction product. The mixes are vulcanized in a mold for 60 minutes at 25 pounds steam pressure. Samples of the resulting stocks are aged during 8 weeks in air at 158 F. Values are given below:

Kilocycles Blank 88 reaction product 120 Eat-ample 8Rearranged reaction products of ketones and amino compounds. 105 parts of acetone-aniline reaction product, prepared by reacting under heatand pressure aniline and acetone in the presence of a dehydrating agent such as iodine as described in my copending application Serial No. 411,665, filed December 4, 1929 were mixed with 100 grams of aniline and cc. of concentrated aqueous hydrochloric acid. The mixture was kept at a temperature of 90 C. during hours. At the endof 30 hours the'hydrochloric acid was neutralized with caustic soda and unreacted aniline was removed by vacuum distillation. The residue weighed 120 grams and became brittle on cooling. It can be ground to a light brown powder. The product was tested by incorporating 1.5 parts in a tire tread compound as in Example 6, and vulcanizing and ageing as described above. The tensile strengths before and after ageing are shown Aged 168 hrs. in oxygen (Cure) at 45% 1310 3440 (Cliff?) at 45%, 1250 3250 (Cure) at 45% 1180 3115 The accelerating properties of the reaction product is shown by incorporating 1.5 parts of the reaction product in a tire tread compound similar to that above but from which 'the usual accelerator was omitted.

Cure 7 Tensiles Blank 90' at 45% 1830 reaction product 90 at 45% 3595 The acceleratingproperties are also shown by incorporating 1 part of the reaction product in a rubber mix consisting of parts of rubber, 10 parts of zinc oxide, and 3 parts of sulphur.

Cure Tensiles Blank-mo accelerator 00 at 40% 402 reaction product. 60 at 40%, 2245 The simplest acetone aniline reaction prodnot, on rearranging in the presence of aniline hydorchloride, would yield a product of the probable formula 0113 oarnnnz which can be called p,p-diamino-di-phenyldi-methyl methane. The reaction product of one mole of mesityl oxide and one mole of aniline on rearranging would yield a compound of the probable formula:

not upon rearranging would yield a product of the probable formula It is obvious that the above and similar products correspond to the probable general formula NHzArCAr-NH;,

wherein A1 and Ar are similar or dissimilar arylene groups, and R and R are aliphatic hydrocarbon groups which may be saturated or unsaturated.

Rearranged ketone-amine reaction prod ucts may be made by rearranging in the presence of aromatic amine salts generally. For example instead of using aniline hydrochloride as in the example above, the hydrochloride of naphthylamine or of diphenyl guanidine may be used. Also when the amine used in the preparation of the ketone-amine is different from the rearranging amines, rearranged ketone-amines of a mixed character result. For example the reaction product of acetone and alphaor beta-naphthylamine may be rearranged in the presence of aniline hydrochloride, and the reaction product of acetone and 4,4-di amino-diphenyl amine may be rearranged in the presence of toluidine hydrochloride.

Escample .9Aldehyde derivative of a rearranged ketone-amine reaction product 82 grams of acetone-aniline reaction product,

which had been rearranged in the presence of aniline-hydrochloride, are melted in 100 cc. of water, and 1 drop of concentrated hydrochloric acid and 10. grams of 37% aqueous formaldehyde are added. The mixture is held at atemperature of C. during 30 minutes; the mixture is then cooled. The resin thus obtained is separated from the water and dried. By this treatment with formaldehyde the rearranged acetone aniline, which is a rather sticky resin, is changed into a hard resin which'may be easily powdered.

An example of the use of this chemical in rubber is as follows: 1.5 parts were incorporated as described above in a standard tire tread stock. The mix was vulcanized and aged under the conditions described above. A blank containing no antioxidant was vulcanized and aged under the same conditions. The tensile tests before and after ageing are as follows:

Green tensiles Blank 33 32? Aged 168 hrs. in oxygen 60 at 45# 1620 3160 at 459$.-- 1475 3120 at 451?; 2040 2840 Aged 3 weeks at 158 F.

Example 10Aldehyde derivatives of a reaction product of a ketone and an amine sa1tTo ten parts of reaction product of acetone and diphenyl guanidine hydrochloride are added 20 parts of 37% aqueous formalde hyde solution. Thetemperature rises from 20 C. to approximately 37 0., and a red viscous oil separates. The reaction is allowed to proceed at room temperature during 16 hours or longer. The reaction product is then taken up in ether and the ether removed by distillation. The residue can be used without further purification. Yield 11 parts. This material. was tested in a rubber mix as describedabove, with the following results:

Instead of formaldehyde, acetaldehyde, aldol, butylaldehyde, crotonaldehyde, heptaldehyde, etc. may be used in Examples 9 and lOto produce the corresponding derivatives. 7

It is to be understood that a mixture of the reaction products or derivatives may be used in rubber instead of a single reaction prodnot or derivative. Also that a mixture of ketones, or a single ketone may be reacted with a single amino compound orwith a mixture of amino compounds or salts thereof, such as described herein, to give products that may be used in rubber in the same manner.

The chemicals disclosed may be used to improve the properties as mentioned herein'of innertubes, tires, thread, hose, dipped goods, mechanical goods, latex or articles made. from latex etc.

Salt of an aromaticamino compound and W amine salt in the claims are to be understood as meaning the acid addition product of the amines or amino compounds, such as thehydrochloride, the sulfate, the phosphate, the acetate, etc. Also the term rubber is to be construed as including natural rubber, gutta peroha, balata, synthetic rubber, or other rubber-like materials.

This case is a division of applicationSerial N 0. 411,666, filed December 4, 1929.

With the detailed description given above, it will be obvious that modifications will suggest themselveswithout departing from the principle of'the invention, for example in the preparation of any of the hereinmentioned compounds, the corresponding thioketone or the corresponding 'ketone dihalide may be used in-place of a ketone, and it is not desired to limit the invention otherwise than as set forth in the appended claims.

-Having thus described my invention, What I claim and desire to protect by Letters Patentis: p

1. A method of treating rubber which comprises treating rubber with an aldehyde dcrivative of a compound having the probable formula I i wherein Ar and Ar are each aromatic groups comprising amino nitrogen, and R and R are hydrocarbon groups which may be saturated or unsaturated.

2. A method of treating rubber which com-- prises treating rubber with an aldehyde de- 0 rivative of a compound having the probable formula T wherein Ar and Ar are each aromatic groups comprising amino nitrogen, and R and R arealiphatic hydrocarbon groups which may be saturated or unsaturated.

3(A method of treating rubber which com- 6 recon i0 and .a salt of an aromaticamine.

4. Amethod of treati-ng rubberwhich com- :pnises treating rubber with a formaldehyde derivative-of :the reaction product of a 'ketone and :an aromatic amine isalt.

5.. A. method of treating rubber which comprises treating rubber with a formaldehydederivativeiofthe reaction product of an aliphatic ketone and an aromatic amine salt. .26. A method of treating rubber which comprises treating rubber with 9. formaldehyde derivative of the reaction product of acetone and :a primary aromatic amine s alt.

Z. A method of treating rubber which comipnises itneatingl with .a formaldehyde derivative of the reaction product ofacetone and aniiinehydroehloride.

:8. A method of improving :the properties of rubber ,uvlhlichv comprises vulcanizing rubberrin thepiresenee of an aldehyde derivative ofvthe reaction product of :a ketone and :a salt of anaromatic' amino compound.

:9..A1m.ethod of improwing the properties of rubber which comprises vulcanizing rubber in the presence ofaformaldehyde derivative of reaction product .of 1a ketone and an aromatic amine 10.. Amethod of improving the properties of rubber which comprises vulcanizi-ng rubher in the presence of :a formaldehyde derivative of reaction product of .an aliphatic kctone and an aromatic amine salt.

11. A mothodwo'f improving the properties of rubber which comprises vulcanizing rubberiin the presence of a formaldehyde derivativeof the reaction product of acetone and a primazyaromatic amine sailt.

. .12. A method of improving :the properties at rulfiier which comprises vulcanizing rubber in the presence of a formaldehyde. derivati-ve of the reaction product of acetone and aniline hydrochloride. I 1 1 13.. A of improving the properties of rubber which comprises vulcanizing rubher in the presence of a formaldehyde derivative of the reaction product of acetone and diphenyl guanidine hydrochloride.

14. A method of treating rubber which comprises treating rubber with an aldehyde derivative of a compound having "the probable formula wherein A1- and A1" are each similar or dissimilar arylene groups, and R and R are each aliphatic hydrocarbon groups which may be saturated or unsaturated. a '15. Aninethodof treating rubber-which comprises treating rubber with an aldehyde derivative of, a rearranged ketone-aromatic amino compound reaction product. I

ld/A method of treating rubber which comprises treating rubber with an aliphatic aldehydederivative of a rearranged Ialiphatic ketone-aromatic amine reaction product. I

17. A method of treating rubber which comprises treating rubber with an aldehyde derivative of a rearranged aliphatic lketonearomatic amine reaction product.

18. A method of treating rubber which comprises treating rubber with a formaldehyde derivative of a rearranged :ketoneprimary aromatic amine reaction product.

19. A method of treating rubber which comprises treating rubber with a formaldehyde derivative ofa rearranged acetone-primary aromatic [amine reaction product.

:20. A method of treating rubber which comprises treating .rubber with a formaldehyde derivative of rearranged acetone-aniline reaction product.

21. A method of improving the properties of rubber which comprises vulcanizing rubber in the presence of an aldehyde derivative of a rearranged ketone-aromatic amino compound reaction product.

22. A method of improving the properties of rubber which comprises vulcanizi-ng rubber in the presence ofan aldehydederivative of a rearranged aliphatic ketone-aro-matic amine reaction product.

23. A method of improving the properties of rubber which comprises vulcan-izing rubber in the presence of 3. formaldehyde derivative of a rearranged ketone-aroma-tic famine reaction product. 7

.24. Amethod of iinprovingthe properties of rubber which comprises vu-lcan-izing rubberin the presence ofa iormaldehyde derivative of a rearranged acetone-primary aromatic amine reaction product.

25.. A method of improving the properties of rubber whichcompr'ises vulcanizing rubber in the presence of a formaldehyde derivative of rearranged acetone-aniline reaction product. p

26... A rubber product which has been treated with .an aldehyde derivative of a rearranged ketone-aromatic amino compoundreaction product.

27. A rubber product which has been treated with an aldehyde derivative of a rearranged aliphatic ketone-aromatic .amine reaction product.

28. A rubber product which has been treated with a formaldehyde derivative of a rearranged ketone-aromatic amine reaction product. 1 V

29. A rubber product which has been treat .ed with a formaldehyde derivative of a rearranged acetone-primary aromatic amine reaction product.

30. A rubber product which has been treated with a formaldehyde derivative of a rearranged ,acetone-aniline reaction product.

31. Avulcanized rubber product containing rubber which has been vulcanized in the presence of an aldehyde derivative of a rearranged ket0ne-aromatic amino compound reaction product.

32. A vulcanized rubber product containing rubber which has been vulcanized in the presence of an aldehyde derivative of a rearranged aliphatic ketone-aromatic amine reaction product.

33. A vulcanized rubber product containing rubber which has been vulcanized in the presence of a formaldehyde derivative of a rearranged ketone-aromatic amine reaction product.

34. A vulcanized rubber product containing rubber which has been vulcanized in the presence of a formaldehyde derivative of a rearranged acetone-primary aromatic amine reaction product.

35. A vulcanized rubber product containing rubber which has been vulcanized in the presence of a formaldehyde derivative of a rearranged acetone-aniline reaction product.

Signed at Montclair, county of Essex, State of New Jersey, this 2Ath day of July 1931.

WILLIAM P. TER HORST. 

